The present invention relates generally to electronic tracking systems and, more particularly, to a tracking system utilizing a highly miniaturized position determination and communications module which may be readily concealed, including on the person of an individual to be located.
Wireless geographic position determination systems have evolved to the point where they are commercially affordable and are now important in many applications, including terrain mapping, vehicle tracking, and so forth. Although early ground-based systems such as Loran-C were lacking in accuracy and reliability, with the advent of GPS or global positioning satellite systems, very accurate and reliable geographic fixes may be obtained. U.S. Pat. No. 5,225,842 xe2x80x9cVehicle Tracking System Employing Global Positioning System (GPS) Satellitesxe2x80x9d provides a useful background, including technical descriptions of previous and existing geographic positioning systems, including the GPS infrastructure.
Along with the evolution of satellite-based positioning systems, telecommunications networks have also evolved to allow mobile communications using very small transceivers, for example, with the hand-held telephones now commonly employed for cellular communications. The advantage of a cellular network, of course, includes the ability to send and receive calls despite changing position within a particular service area.
In some situations, it makes sense to integrate the capabilities of wireless geographical positioning with mobile telecommunications. For this reason, various vehicle tracking systems have evolved which combine certain aspects of satellite-based and mobile communications, including cellular telephony. Once such application is described in U.S. Pat. No. 5,223,844 xe2x80x9cVehicle Tracking and Security System,xe2x80x9d wherein mobile units include vehicle theft and intrusion protection facilities along with a receiver of signals from a global positioning satellite system. In the event of a security breach, the remote unit automatically communicates position information to a fixed control center over a mobile phone network, enabling the center to monitor the vehicle to solve a problem or apprehend an offender.
It is clear from the above and other references which combine positioning and communications capabilities, however, that miniaturization to an extent which affords concealment within very small remote units to be tracked or on an individual have not been considered. Existing systems, while making an effort in certain cases to hide some or all of their associated components, have not been further required to substantially miniaturize such components, since, particularly in vehicular applications, sufficient volume and operating power are available to operate off-the-shelf constituents without dramatic reductions in physical size. However, if an electronic tracking system is to be concealed within smaller objects or worn on the person, dramatic changes must be made not only to the enclosure and the structure of the components contained therein, but steps must also be taken to manage power control to ensure that power is not drained before such a system becomes critically necessary.
One aspect of the invention provides a miniaturized geographic position determination and communications module in a small, concealable enclosure. In the preferred embodiment the enclosure is in the form of a thin capsule, enabling the enclosure to be hidden in very small spaces, including concealment on the person. Electronic circuitry and a source of power are contained within the enclosure, with the circuitry including a global positioning satellite receiver, a communications transceiver, and a controller. The controller is at least able to cause the global positioning satellite receiver to receive and decode a signal relating to the geographic position of the module; cause the communications transceiver to communicate the geographic position information to a remote location; and disable the global positioning satellite receiver and communications transceiver when not in use so as to conserve power from the source. The geographic position information may be communicated to a remote location either in response to the activation of a panic function, or after receiving a request from a remote location, which then commences the transmission in response to the request. The controller is preferably further operative to perform a functional self-test of the global positioning satellite receiver and communications transceiver to ensure they are in proper working order.
In terms of physical construction, electronic circuitry of the module is preferably mounted on at least one thin substrate, and in the case of two or more, they are disposed parallel to one another and electrically interconnected within the enclosure. A thin battery is preferably used the power source, and a thin antenna associated with the global positioning satellite receiver is supported on the enclosure. The substrate(s), battery and antenna may thus be supported parallel and in close proximity to one another, enabling all components to be contained on or within a small, capsule-like enclosure.
In a system-level configuration, the miniaturized, readily concealable module is used in conjunction with a portable locating unit operative to receive the geographic position information at the remote location and inform a user as to the location of the miniaturized module. Preferably the portable locating unit further includes a positioning satellite receiver of its own and a display, enabling the locating unit to visually indicate the location of the miniaturized module relative to that of the locating unit.